1. Field of the Invention
The invention relates to a photographing apparatus such as a video camera or the like.
2. Related Background Art
In video cameras, a small size and a light weight are realized by putting a solid state image pickup device into a practical use and a number of video cameras are rapidly spread by the realization of a high magnification and multi-functions. In recent years, the exposure control and focusing control are automated and the number of failures of the photographing operations due to those controls is small. However, the video camera is ordinarily used at a hand-gripping position. There is a large possibility of the hand-blurring in association with the realization of the light weight and small size. In almost all of the hand-gripping cases, the photographed picture planes are certainly blurred. A deterioration in picture quality due to such a blurring of the picture plane and an unpleasant feeling such as a video sickness or the like causes a problem.
As disclosed in U.S. Pat. Nos. 2,959,088 and 2,829,557, as means for suppressing or eliminating such a picture plane blurring, there are known constructions such that a correction optical system of the self-supporting driving type by an inertia force is arranged and the image blurring is corrected by the inertia operation for the camera blurring and using an optical decentering apparatus such as a variable apex angle prism or the like which can be freely driven from the outside. In the above constructions, fundamentally, the optical axis of the photographing optical system is decentered in such a direction as to eliminate the blurring of the photographing apparatus main body. The variable apex angle prism has a construction such that the peripheries of two transparent plates which are away from each other in the optical axis direction are closed by bellows and the inside of them is filled with a liquid of a predetermined refractive index. The photographing optical axis is decentered by inclining the transparent plate locating on the object side for the plane which crosses perpendicularly to the center axial line (optical axis at the neutral position).
As a construction to correct the blurring by image signal processes, there has been proposed and put into practical use a blurring correcting apparatus or a vibration isolating apparatus in which an image pickup device having an image pickup area wider than an ordinary display area is used and an image area for a video output in an output of the image pickup device is selected from the output of the image pickup device in accordance with the camera blurring detected by image signal processes.
However, the former blurring correcting apparatus has a problem such that a special optical system for blurring correction and its driving system are needed and the construction becomes complicated. In the case where the blurring correction is not executed, an apparatus using optical axis decentering means such as a variable apex angle prism or the like merely causes a loss of light amount.
On the other hand, the latter apparatus for correcting the blurring by the image signal processes uses the image pickup device having horizontal and vertical pixels of the number exceeding the ordinary number of horizontal and vertical pixels. Upon blurring correction, the image output area is moved horizontally and vertically in the image pickup area in accordance with the camera blurring amount and direction, thereby suppressing or eliminating the camera blurring. When the blurring correction is not performed, the image output area is ordinarily located at the center of the image pickup area and the image information in the areas out of the image output area is not used at all.
In the latter blurring correction apparatus by the image signal processes, the image pickup device having the horizontal and vertical pixels of the number exceeding the ordinary number of horizontal and vertical pixels is used or, in the case of the image pickup device having the ordinary number of horizontal and vertical pixels, an image signal process to magnify an output of the image pickup device is needed. In any of the above two cases, the image information which is not ordinarily used is held for the blurring correction and the image information of the areas out of the range which is necessary for the blurring correction is abandoned. A circuit larger than the ordinary circuit must be prepared as an image processing circuit to process a larger amount of image information. In other words, excessive image information and excessive image signal processing circuit exist and are used only when the blurring is corrected.
The same applicant as the present invention has already filed the following inventions with respect to the blurring correction: U.S. Pat. No. 5,012,270; U.S. patent application Ser. Nos. 403,455 (filed on Sep. 6, 1989), 708,199 (filed on May 31, 1991), and 422,025 (filed on Oct. 16, 1989); U.S. Pat. No. 5,031,049; U.S. patent application Ser. No. 240,915 (filed on Sep. 6, 1988); and the like.